With the development of services such as video on demand, high definition TV, and network games, requirements of a subscriber on the bandwidth are ever increasing, and development of Fiber To The Home (FTTH) can effectively guarantee the access network bandwidth of “last mile”. Among others, a Passive Optical Network (PON) technology is one of the most widely applied FTTH technologies currently.
In an existing PON system, for example, a Gigabit-PON (GPON), although the system has various monitoring and maintenance functions, and specifies alarm indications, performance events, and administration between Optical Line Terminals (OLTs) and an Optical Network Unit (ONU) in detail, the GPON is only applicable to a situation in which the OLTs and the ONU are directly interconnected by using optical signals in the conventional PON system. In an electrical relay Long Reach-PON (LR-PON) application, if necessary monitoring and processing are not performed in an electrical relay device, the previous alarm indications and maintenance functions can only be transparently transmitted, while the fault of an intermediate node cannot be analyzed and located. Therefore, Operation Administration and Maintenance (OAM) is required for the LR-PON device.
An existing method for transferring OAM information between the LR-PON device and the OLT device is as follows: In an upstream direction from the LR-PON device to the OLT device, a line rate is increased, and the OAM information between the LR-PON device and the OLT device is accommodated within the increased rate. Specifically, the method includes:
(1) a new upstream frame structure is defined, where in addition to accommodating the original PON data stream, the frame structure further needs to define a space for accommodating the OAM information;
(2) in a PON over Optical Transmission Network (OTN), a PON over Synchronous Digital Hierarchy (SDH)/Synchronous Optical Network (SONET), or a similar manner, the PON data stream is used as payload of the OTN, the SDH or the SONET, and is transferred through a transport network, and the OAM information of the LR-PON device is transferred through a communication channel formed by overhead bytes of the OTN, the SDH or the SONET.
However, the method requires a higher line rate and modification to the existing PON system, and is incompatible with the existing OLT device. Furthermore, the method requires support from transport networks used in pair back-to-back, and a transport network device near the OLT device is further required to establish a communication channel with the OLT device. Additionally, in the transport network device, format conversion from the OAM information of the LR-PON/OLT device to the transport network overhead is required. Therefore, the implementation of the method is complex, and the cost is high.